1. Field of the Invention
The present invention relates to a charge pump.
2. Description of the Related Art
Electronic devices often require regulated voltages in order to operate properly. Typically, a supply voltage of the device is provided to a voltage regulator which can translate the voltage to an output voltage at different levels. Various types of voltage regulators can be used. For example, linear regulators provide a relatively noise free output and can be lower in cost, but are less efficient and unable to step-up or invert the input voltage. Switching regulators can be higher in cost but have greater efficiency and can provide step-up and inversion features. Switching regulators rapidly switch an energy storage device such as an inductor or capacitor on and off. A charge pump, or voltage converter, provides an output voltage which is different from the supply voltage. A charge pump typically uses capacitors as energy storage elements to provide an output voltage which is higher or lower than the input voltage. Moreover, a charge pump can include voltage regulation circuitry to maintain the output voltage at a constant level also in the case when the input voltage varies within a range. However, a charge pump usually suffers from efficiency degradation when operated at a point which is not close to its native input to output voltage ratio.